Complete rear idler cog sprocket assembly for 125cc GY6 QMI152/157 and 150cc GY6 QMJ152/157 engines Includes friction gear, cog sprocket, shaft, washer, pin, and springDescription Complete rear idler cog sprocket assembly for 125cc GY6 QMI152/157 and 150cc GY6 QMJ152/157 engines. Includes friction gear, cog sprocket, shaft, washer, pin, and spring.This rear idler cog sprocket assembly is used on a wide variety of scooters and ATV brands and models that have Chinese built 125cc GY6 QMI152/157 and 150cc GY6 QMJ152/157 engines. ? WARNING California Residents: Proposition 65 Warning